Abstract: When tunnel boring machine tunneling in complex geological conditions, such as extremely uneven soft and hard rock with hardness exceeding 180 MPa, the cutter′s rock breaking efficiency is low and cutterhead jams occur. To address these issues, a rockbreaking test is conducted on granite samples using a disc cutter rockmachine interaction comprehensive test platform equipped with a highpressure water jet device. The influence of water jetassisted mechanical disc cutter rockbreaking on tunneling parameters and efficiency under various conditions is investigated using various water jets and tunneling parameters. The reasonable target distance and pressure of water jet rockbreaking are obtained, as well as the crosstrack of the water jet and mechanical disc cutter, the change characteristics of thrust, torque, and rockbreaking efficiency of the cutterhead of the same track composite rockbreaking and relatively pure mechanical disc cutter rockbreaking are validated.